Removal of humate from bayer alumina liquors

Abstract

A process is disclosed for reducing the turbidity of a Bayer process liquor containing a cationic polymer-humate complex comprising adding to said liquor a higher molecular weight, cationic polymer.

We claim: 
     
       1. A process for reducing the turbidity of a Bayer process liquor containing a cationic polymer-humate complex, wherein the cationic polymer of the cationic polymer-humate complex is a water soluble catonic quaternary ammonium slat having an intrinsic viscosity of about 0.1, which comprises adding to said liquor an effective amount of a second, higher molecular weight, cationic polymer to flocculate said cationic polymer-humate complex and thereafter removing the resultant flocculated polymer-humate complex from said liquor to reduce said turbidity. 
     
     
       2. The process of claim 1 wherein the complex is a polydiallyldimethylammonium chloride-humate complex and the second, higher molecular weight, cationic polymer is 90/10 to 0/100 acrylamide/dimethylaminoethylacrylate methyl chloride. 
     
     
       3. The process of claim 1 wherein the complex is a polydiallyldimethylammonium chloride-humate complex and the second, higher molecular weight, cationic polymer is 90/10 to 10/90 acrylamide/diallyldimethyl ammonium chloride. 
     
     
       4. The process of claim 1 wherein the complex is a polydiallyldimethylammonium chloride-humate complex and the second, higher molecular weight cationic polymer is 90/10 to 0/100 acrylamide/methylacrylamidopropyltrimethyl ammonium chloride. 
     
     
       5. The process of claim 1 wherein the complex is a polydiallyldimethylammonium chloride-humate complex and the second, higher molecular weight, cationic polymer is 90/10 to 0/100 acrylamide/dimethylaminoethylmethacrylate methyl chloride. 
     
     
       6. The process of claim 1 wherein the second, higher molecular weight, cationic polymer is derived from a monomer having the formula:   CH.sub.2 ═C (R)CONHR.sup.1 NR.sup.2 R.sup.3     wherein R is hydrogen or methyl, R 1  is a straight or branched chain C 2  -C 8  alkylene group and R 2  and R 3  are, individually, C -  -C 4  alkyl, and their quaternized counterparts.